Why using is used here

public class OutboxWorker(ILogger<OutboxWorker> logger, IServiceScopeFactory serviceScopeFactory, IEventPublisher eventPublisher) : BackgroundService
{
    protected override async Task ExecuteAsync(CancellationToken stoppingToken)
    {
        while (!stoppingToken.IsCancellationRequested)
        {
            using (IServiceScope scope = serviceScopeFactory.CreateScope())
            {
                var db = scope.ServiceProvider.GetRequiredService<OrdersDbContext>();
                var outboxItems = db.Outbox.Where(item => !item.Processed);

                foreach (var item in outboxItems)
                    {
                            logger.LogInformation("some operation is done")
                            item.Processed = True
                            break;
                    }
                    
                    db.Outbox.Update(item);
                }

                await db.SaveChangesAsync(stoppingToken);
            }
            
            await Task.Delay(5000, stoppingToken);
        }
    }
}